The present invention relates to waterborne basecoat compositions having particular utility in multi-layer coatings such as vehicle basecoat/clearcoat (BC/CC) applications. The basecoat compositions of this invention can be used in either original equipment manufacturer (OEM) production lines or in automotive vehicle refinish (VR) body shops and the like.
Multi-layer coatings for use over the surface of automobiles, trucks and the like have been in use for years. Originally, such coating systems used organic solvents. As environmental concerns and regulations became more prevalent, such organic solvent-based systems fell out of favor. In recent years, the development of waterborne systems has increased. In particular, the development of waterborne basecoats as part of a volatile organic content (VOC) compliant basecoat/clearcoat system has increased. Many of the world's large coatings companies have disclosed waterborne basecoats for use in basecoat/clearcoat vehicle coatings. By way of example, BASF, DuPont, ICI and PPG all have patents in this area: U.S. Pat. No. 5,204,401 (Anderson et al., BASF) teaches metallic and nonmetallic waterborne basecoats having a water-reducible acrylic resin with nonionic and acid functionality derived from vinyl monomers having nonionic and urethane functionality. U.S. Pat. No. 5,169,719 (Balatan BASF) teaches water-dilutable polyurethane/acrylic copolymers useful as the principal resin and as pigment grind resins in waterborne automotive basecoats. U.S. Pat. No. 5,157,069 (Campbell, BASF) teaches an aqueous coating comprising a nonionic dispersion of a polymer selected from the group consisting of acrylic resin, polyurethane resin (and mixtures thereof) with a nonionic water soluble rheology control polymer (such as a polyether, cellulose, cellulose derivative, polyvinylalcohol, etc.) and pigments. U.S. Pat. No. 5,066,732 (Savino et al., BASF) teaches water dispersible nonionic polyurethane resins having polyether backbones. U.S. Pat. No. 5,017,673 (Balatan, BASF) teaches water dispersible nonionic polyurethane resins having polyester backbones. U.S. Pat. No. 4,978,708 (Fowler et al., BASF) teaches an aqueous basecoat containing an anionic polyurethane resin and an anionic acrylic pigment grind resin. U.S. Pat. Nos. 4,558,090 and 4,489,135 (Drexler et al., BASF) teach a process and composition useful as a basecoat in a multilayer coating wherein the basecoat is an aqueous polyurethane. U.S. Pat. No. 5,204,404 (Werner Jr., et al., DuPont) teaches waterbased coating compositions containing an acrylic silane polymer and a polyurethane polymer. U.S. Pat. No. 5,051,464 (Johnson et al., DuPont) teaches a waterbased coating composition containing an acrylourethane pigment dispersing polymer and a binder. U.S. Pat. Nos. 5,006,413 and 4,954,559 (Den Hartog et al., DuPont) teach waterbased coating compositions containing a methylol (meth)acrylamide acrylic polymer binder and a polyurethane. U.S. Pat. No. 5,100,735 (Chang, DuPont) teaches an improved process for forming a multilayer finish on an automobile comprising using a waterborne acrylic basecoat and a high solids, solvent-based acrylic, polyester, or polyesterurethane clearcoat with an alkylated melamine formaldehyde crosslinking agent. U.S. Pat. No. 4,403,003 (Backhouse, ICI) teaches a process for producing a multilayer coating wherein an aqueous dispersion pigmented basecoat containing crosslinked microparticles is first applied. U.S. Pat. No. 4,822,685 (Perez et al., PPG) teaches a method of forming a multilayer coating over a substrate wherein an aqueous-based polyurethane dispersion is used as a pigmented basecoat. U.S. Pat. No. 4,719,132 (Porter Jr., BASF) teaches an aqueous basecoat comprising an aqueous polyurethane resin.